qa/workunits/fs/misc: Add workunit for file lock deadlock detection

Signed-off-by: Yan, Zheng <zyan@redhat.com>

diff --git a/qa/workunits/fs/misc/filelock_deadlock.py b/qa/workunits/fs/misc/filelock_deadlock.py
new file mode 100755 (executable)
index 0000000..a344761
--- /dev/null
+++ b/qa/workunits/fs/misc/filelock_deadlock.py
@@ -0,0 +1,68 @@
+#!/usr/bin/python
+
+import time
+import os
+import fcntl
+import errno
+import signal
+import struct
+
+def handler(signum, frame):
+    pass
+
+def lock_two(f1, f2):
+    lockdata = struct.pack('hhllhh', fcntl.F_WRLCK, 0, 0, 10, 0, 0)
+    fcntl.fcntl(f1, fcntl.F_SETLKW, lockdata)
+    time.sleep(10)
+
+    # don't wait forever
+    signal.signal(signal.SIGALRM, handler);
+    signal.alarm(10);
+    exitcode = 0;
+    try:
+        fcntl.fcntl(f2, fcntl.F_SETLKW, lockdata)
+    except IOError, e:
+        if e.errno == errno.EDEADLK:
+            exitcode = 1
+        elif e.errno == errno.EINTR:
+            exitcode = 2
+        else:
+            exitcode = 3;
+    os._exit(exitcode);
+
+def main():
+    pid1 = os.fork()
+    if pid1 == 0:
+        f1 = open("testfile1", 'w')
+        f2 = open("testfile2", 'w')
+        lock_two(f1, f2)
+
+    pid2 = os.fork()
+    if pid2 == 0:
+        f1 = open("testfile2", 'w')
+        f2 = open("testfile3", 'w')
+        lock_two(f1, f2)
+
+    pid3 = os.fork()
+    if pid3 == 0:
+        f1 = open("testfile3", 'w')
+        f2 = open("testfile1", 'w')
+        lock_two(f1, f2)
+
+    deadlk_count = 0
+    i = 0
+    while i < 3:
+        pid, status = os.wait();
+        exitcode = status >> 8
+        if exitcode == 1:
+            deadlk_count = deadlk_count + 1;
+        elif exitcode != 0:
+            raise RuntimeError("unexpect exit code of child")
+       i = i + 1
+
+    if deadlk_count != 1:
+        raise RuntimeError("unexpect count of EDEADLK")
+
+    print 'ok'
+
+main()